The present invention relates to disposable paperboard cartons, more particularly to cartons constructed from a single integral flat blank of paperboard having a pull tab tear strip for easy opening. The tear strip opening feature may be located at either end or side of the container. The cartons are typically used to package, store, ship and sell product at retail for consumer use. The requirements, therefore, are for the carton to be sealed to effect an end panel closure, and should provide ease of opening for gaining access to the contents of the container.
Numerous types of opening features are known in the prior art. U.S. Pat. No. 3,410,476 illustrates opening features similar to the subject invention. This patent discloses a reclosable carton having a tear strip comprised of a plurality of linearly positioned slits provided with continuous cut score lines extending the length of the slits. U.S. Pat. No. 3,524,581 also discloses a tear strip utilizing both a fracture line and a cut score line. Neither patent, however, discloses a tear strip which contains a line of herringbone perforations on one side and a cut score line on the other.
U.S. Pat. No. 4,538,732 discloses a tear strip for use on a relatively narrow side wall of a flat paperboard carton. This tear strip also operates on the principal of ply separation but does not contain an underside cut score line for defining a point of weakness for the beginning of ply separation. The improved feature of this invention provides better, easier, and more predictable separation of the plys.